A wide variety of power take-off units have been proposed in the art. The PTOs are used in conjunction with the power transmissions of trucks, tractors and other motor vehicles to provide auxiliary power transmission for such things as driving compressors on refrigerated trucks, operating auxiliary farm equipment, operating fire truck accessories, operating tailgates and lifts on trucks and the like. Generally, the power take-off unit is mounted on the main transmission so that an idler gear in the take-off engages a transmission gear for driving the PTO. Conventionally, a PTO is mounted on the transmission case at either a "5 or 7 o'clock" position, such that lubricating oil from the oil sump of the transmission, gear box or transfer case flows by gravity into the PTO housing for lubricating the PTO components.
The prior art, however, does not teach an acceptable system for providing lubrication to the PTO housing in the instances where the PTO is mounted on the transmission case above the oil level in, for example, the transmission sump, such as at a "10 or 2 o'clock" position.
In view of the deficiency associated with conventional PTO lubrication systems, there is a need in the art for a PTO unit that includes a lubrication system which provides lubrication to the internal components of the PTO unit mounted above the oil level of the transmission sump, and which is operable only when the PTO is in operation.